eChapters

Vulnerability of Soils

Soil vulnerability, Soil degradation, soil vulnerability index

Water and wind erosion, depletion of soil organic matter, loss of plant nutrients, salinity, alkalinity, acidity, pollution and contamination, compaction, sealing, crusting, water-logging, aridity, lowering of water table, over grazing, deforestation, landslide, loss and change in soil biodiversity, Abandoned mines etc.

Soil vulnerability, Soil Degradation, Soil Vulnerability Index

The terms vulnerable and vulnerability are now bites of every one and used for everything. Vulnerable means to the possibility of attack or harm by any mean. Human beings are vulnerable to Covid-19, computers are vulnerable to virus, softwares are vulnerable to hackers and attackers to control system, environment is vulnerable to pollution. Vulnerabilities refer to the lack of ability to resist the effects of the aggressive environment. Soils are vulnerable to numerous threats like water and wind erosion, depletion of soil organic matter, loss of plant nutrients, salinity, alkalinity, acidity, pollution and contamination, compaction, sealing, crusting, water-logging, aridity, lowering of water table, over grazing, deforestation, landslide, loss and change in soil biodiversity etc. However, this book will describe some of the most pertinent vulnerabilities for soils.

8.1. Warehousing

8.1.1. Definitions

Defined as the assumption of responsibility for storage of goods.

Protector of national wealth, for the produce stored in warehouses is preserved and protected against rodents, insects and pests and against the ill effect of moisture and dampness.

Introduction

A variety of glassware, plasticware, and other apparatus are used for experimental purposes in a laboratory. They need to be washed, cleaned, dried, and sometimes sterilized before they can be used in the next set of experiments. Glassware needs special care of handling during washing, drying, sterilization, etc. because even a minor mistake in handling of glassware may result in its cracking/breakage and it may become unserviceable. All of these may result in a delay in experimentation if spare piece of the glassware is not available or it may affect serviceability of the associated apparatus.

A large number of glassware such as beaker, flask, measuring cylinder, burette, test tube, etc. are regularly used in a laboratory, which requires careful handling during the different stages of experiment as well as after completion of the experiment while preparing them for another set of experimentation.

Glass being a complex silicate, its properties depends on the type of silicate anions in the structure and the cations formed. Thermal properties of glass changes by the addition of boron oxide (B2 O3 ); hence, borosilicate glass is extensively used in the laboratories. With this brief background information, let us discuss about the necessity, procedures, and precautions during washing, cleaning, drying and sterilization of laboratory-wares. Figure 3.1 shows various advantages of using borosilicate glass in a laboratory.

Good laboratory practices require clean glassware, because an experiment may give erroneous result if dirty glassware is used at any step of the experiment. Hence, the glassware must be physically and chemically clean; and in many cases, it must be microbiologically clean or sterile. The commonly used glassware in a laboratory include test tube, measuring cylinder, pipettes, beakers, flasks, microscopic slides, etc.

Introduction

Waste management and soil sustainability are two critical aspects of environmental conservation and sustainable development. As our global population continues to grow and consume resources at unprecedented rates, it becomes increasingly important to manage waste effectively and preserve our soil health and productivity. Anthropogenic activities have consistently produced waste. The World Bank predicts that worldwide garbage production will rise to 70% by 2050 if no substantial actions are taken (Ghosh, 2020). This was not a significant problem when the world’s population was small; however, it is acquired as a major concern with industrialization and urbanization revolution. Lack of proper waste management has caused pollution of water, land, and atmosphere, as well as a significant effect on human health (Raza et al., 2022a; Raza et al., 2022b).

Introduction

The Indian arid zone covers nearly 31.8 million ha of the country’s geographical area. It mainly spreads over parts of Andhra Pradesh, Gujarat, Haryana, Karnataka, Maharashtra, Punjab and Rajasthan states of India. Six of the eleven districts in Western Rajasthan i.e. Barmer, Bikaner, Churu, ShriGanganagar, Jaisalmer and Jodhpur lie wholly in the arid zone. High temperature, low precipitation and high velocity winds are some of the main culprits of Arid zone which limit the scope for higher crop productivity in these areas. Under this situation, arid horticulture based farming practices has ample scope to raise the productivity and living standard of peoples of the hot arid and semi-arid regions. Arid horticulture based farming practices greatly favour the development of high quality produce in many fruit and vegetable crops. Horticulture based farming practices are now considered to be the most ideal strategy to provide food,nutrition and income security to the people especially in arid and semi-arid region of the country (Chundawat 1993; Chadha 2002).

Today India is the world largest producer of many fruits and vegetables. Wastes and by-products generated from fruits and vegetables are organic in nature and contribute a major share in soil and water pollution. Also, accumulated fruit and vegetable wastes (FVWs) cause greenhouse gas emission which is a matter of serious environmental concern. Proper disposal and handling of these wastes can help reduce pollution risks, at the same time be a source of several useful and commercially valuable by-products. Organized processing of wastes can help farmers achieve higher incomes.

Introduction

Over 250 million people are directly affected by land degradation worldwide. Each year 12 million hectares are lost to deserts. Only 11 % of the global land surface can be considered as prime or Class-I land.

India contains 2.4 % of world’s total land. Out of the total geographical area of 329 million ha of the country, land use statistics are available for about 93 % of the total area which comes around 306 million ha. The arable land (net area sown plus the current and other fallow lands) was estimated at 166.14 million ha (54.2%) while the area under forest was accounted at 69.02 million ha (22.6%). Land put to non-agricultural uses was estimated at 22.97 million ha (7.5%) and the barren and uncultivable land at 19.44 million ha (6.4%). Permanent pastures and other grazing lands where estimated 11.04 million ha. (3.6%), land under miscellaneous uses at 3.62 million ha. (1.2%) and the cultivable waste land at 13.08 million ha (4.5%). By summing up these figures, the reporting area comes out 306 million ha.

2.1. Definition

Land which is presently lying unused or which is not being used to its optimum potential due to some constraints

I. Definition of wasteland

Wasteland include degraded forest, overgrazed pastures, drought- struck pastures, eroded valley, hill slopes, water logged marshy lands, barren lands etc.

Different authors have defined wastelands as:

Land which is lying unproductive or which is not being utilized to its potential.

Land which is incapable of producing material or services of value (American Society of Soil science).

Land which has been abandoned and for which there is no further use (Mine spoils).

Land which produces less than 20% of economic potential. e) Land where no greenery can be sustained.

Land which is neither under forest cover or agricultural cover or assigned for specific purposes such as National park or National hydro power projects.

The Technical Task Group Report of the National Wasteland Board defines the wasteland due to different constraints.

5.1 Sampling

There are different sources of water such as rain, streams, canals, lakes, tanks, ponds, large reservoirs, shallow and deep wells, shallow and deep tube wells, as well as sewage effluents and sea water. The composition of the different sources of water vary with the season, rate of flow, the extent of effluents from the industrial units and sewage effluents from the municipal area during rainy season, the river tank and pond water becomes salty and muddy due to soil erosion. The depth of ground water also varies with the seasons. The sources of water available to the farmer for irrigation of crops are generally few such as canal, shallow and deep wells, pumping sets, tube wells and runoff water collected in excavations along roads, natural drains and adjoining areas under impeded drainage. The composition of water also varies with the season. Whatever may be sources of water, the water sample is taken along with the soil sample to soil testing laboratory for its analysis by way of assessing the suitability of water for irrigation.

For drawing maximum benefit the samples taken be representative of the water in bulk and it should be collected in a clean vessel. One to three litres capacity plastic bottles duly washed with a detergent are satisfactory. However, before filling with water samples the bottles must be rinsed with water samples three times. The information such as farmers name, owner of pumping sets, date and month of sampling depth of ground water, crops and soils being irrigated, any specific agricultural or human problems encountered to be briefly recorded along with the name of village, block, tehsil and district. The water sample should be properly labeled and submitted to soil testing laboratory for its analysis.

A water budget quantitatively accounts for water entering, leaving and remaining within a defined agricultural or hydrological system. Comparable to a financial budget, it considers precipitation, irrigation, runoff, evapotranspiration, percolation and changes in storage. This chapter explains the climatic and soil-water budget, potential and actual evapotranspiration, water surplus, water deficit and moisture adequacy. It discusses how water-balance analysis supports irrigation scheduling, crop planning, drought assessment, rainwater harvesting and watershed management. Understanding the timing and magnitude of water availability helps farmers and planners select crops and management practices suited to local conditions. Water budgeting therefore provides a fundamental tool for climate-resilient and resource-efficient agriculture.

Submerged soils/Flooded soil

Submerged soils are the type of soils that are saturated with water for a sufficiently long time in a year. This gives the soil the following distinctive gley horizons resulting from oxidation-reduction processes:

The soil is intermittently saturated with water, oxidation of organic matter is slow and it accumulated within the “A” horizon. Fe and Mn are deposited as rusty mottles or streaks if the diffusion of O2 into the soil is slow in the second horizon, whereas if the diffusion is rapid, they are deposited as concretions.

Types of submerged soils

1. Waterlogged soils- Waterlogged soils are saturated with water for a sufficiently long time annually to give the soil the distinctive gley horizons resulting from oxidation-reduction processes. Saturation with water may be due to impermeability of the soil material, or the presence of an impervious layer, or a high water table.

2. Marsh Soils- These types of soils are more or less permanently saturated or submerged. Freshwater marshes can be classified according to their origin into upland, lowland, and transitional. Upland marshes are poor in bases and have pH 3.5-4.5 because they receive mainly rainwater. Lowland marshes are saturated or submerged with water-carrying bases and have pH 5.0-6.0.

Introduction
Water management is a critical aspect of agricultural science and environmental sustainability, influencing not only the efficiency of food production but also the health of ecosystems and the balance of global water resources. This chapter delves into the principles, techniques, and modern advancements in water management, emphasizing its significance in ensuring food security, conserving vital resources, and combating global warming. The chapter begins by exploring the foundational principles of irrigation, a key component of water management in agriculture. Various irrigation techniques, such as surface, sprinkler, and drip irrigation, are discussed in detail, along with the factors that influence irrigation efficiency, such as soil type, crop needs, and climatic conditions. The importance of optimizing irrigation practices to enhance water use efficiency and minimize waste is underscored. Water use efficiency and conservation strategies form the next major focus of the chapter. As global water resources face increasing pressure from population growth, industrialization, and climate change, the need for efficient water use in agriculture becomes ever more critical. The chapter discusses various methods to improve water use efficiency, including advanced irrigation technologies, crop selection, and soil management practices. Conservation strategies, such as rainwater harvesting, groundwater recharge, and the use of drought-resistant crops, are also explored. Effective drainage systems and waterlogging control are essential for maintaining soil health and agricultural productivity. The chapter provides an overview of drainage system principles, techniques for assessing soil drainage, and strategies for controlling waterlogging, a condition that can severely impact crop yields. The benefits of well-managed drainage systems, including improved soil structure, reduced salinity, and enhanced crop performance, are highlighted. Water quality and salinity management are crucial for sustaining agricultural productivity and preventing soil degradation. The chapter discusses methods for assessing water quality, the impact of salinity on soils and crops, and techniques for managing salinity, such as the use of salt-tolerant crops and soil amendments. Effective water quality management ensures that crops receive the nutrients they need while preventing harmful buildup of salts and other contaminants

6.1 INTRODUCTION

Water in soils is essential to plant growth, being the medium through which inorganic nutrients are translocated to the root surface and carried through the plant. Most of the water in soils at or near field saturation can be considered as equivalent to bulk water, and only bulk properties need be considered in discussing its movement through soil interstices and its retention in soil capillaries; this is the field with which soil physics deals. But, in the first molecular layer in contact with soil particles, and perhaps for several molecular layers beyond, the behaviour of water molecules is very different from that in the bulk. Strong adsorptive forces can reduce the volatility of these molecules and restrict their mobility. Such an adsorbed layer of water competes with other polar molecules for adsorption sites, and so has an important role in determining the release and retention of fertilizers and pesticides. Such strongly adsorbed layers confer wettability on soils, but hydrophobic surfaces can also be present and these lead to non-wettable soils with serious consequences in run off and inefficient use of precipitation. This region of distinctive molecular interactions between water and soil particles falls within the field of soil chemistry.

The quality of irrigation water is a crucial factor for long-term soil productivity. Poor quality water if used for a long time can make the soil less productive or even barren, depending on the amount and type of constituents present in it and the texture of the soil in question. Low or marginally saline waters sometimes appear to stimulate crop growth because of the higher amounts of nutrient ions present.

Irrigation water always contains some soluble salts irrespective of its source. The suitability of waters for a specific purpose depends on the types and amounts of dissolved salts. Some of the dissolved salts or other constituents may be useful for crops. However, the quality or suitability of waters for irrigation purposes is assessed in terms of the presence of undesirable constituents, and only in limited situations is irrigation water assessed as a source of plant nutrients. Some of the dissolved ions, such as NO₃^- are useful for crops.

Collection of water samples

A representative water sample (500 ml) is collected in a glass or polyethylene bottle, which should be properly washed/rinsed with the same water that is being sampled. Floating debris or any other contaminant should be avoided while collecting the sample. After proper labelling (e.g. source of water, date of collection, and type of analysis required), the sample should be sent to the laboratory without undue delay.
Some of the anions such as SO₄ and NO₃ may be quite low in irrigation waters. Hence, the large volume of the sample has to be first concentrated by evaporating it to about 100 ml in order to obtain their detectable amounts.

Water quality standards (Classification)

Some countries have established national standards and criteria for evaluation and classification of water quality. The classification of irrigation waters has been made according to one or more of the following criteria.

1.    Salinity or total concentration of soluble salts (EC)
2.    Sodicity hazards (SAR)
3.    Alkalinity hazards (RSC)
4.    Combined evaluation on the basis of EC and SAR by USSL diagram
5.    Combined evaluation on the basis of EC and Adj. SAR
6.    Combined evaluation on the basis of EC, SAR and RSC

1.1. Status of irrigation in Tamil Nadu

Geographical area of 13 million hectares is ranked eleventh in size among the Indian states.

Net area sown is about 6 million hectares.

3 million hectares or 50% get irrigation facilities.

4.1. Water Use Efficiency (WUE)

An efficient irrigation system implies effective transfer of water from the source to the field with minimum possible loss.

To identify the nature of water loss and to decide the type of improvements in the system.

Evaluation of performance in terms of efficiency is prerequisite for proper use of irrigation water.

1.1. Watershed development

Refers to the conservation, regeneration and judicious utilization of all the resources viz., land, water, vegetation, animal and human within a particular watershed in integrated manner.

Water drainage area on earth’s surface from which runoff, due to precipitation, flows into a single to a larger stream, a river, a lake or the ocean.

1.2. Concept of watershed management

Planning and design of soil and water conservation structures such as bunds, waterways, overflow structures, water harvesting structure.

Technical Term                            Definition

Geomorphological Analysis       Geomorphological analysis is the systematic description of watershedís geometry and its stream channel system to measure

                                                   the liner aspects of drainage network, aerial aspects of drainage basin and relief aspects of channel network.